The present invention relates to dentifrice containing tannic acid efficacious for the prevention of tooth decay, pyorrhea and gingivitis and to its method of manufacture.
In the field of dental treatment, various studies are being made of late of making oral medicines or dentifrice containing fluorides with the object of preventing or decreasing prevalence of tooth decay in the knowledge that the average rate of outbreak of patients suffering from tooth decay is comparatively lower for those who live in the regions where fluorine is contained in the drinking water in the form of fluorides in a period when their teeth are coming into being and are growing. However, the fact is that the number of patients suffering from tooth decay is increasing year by year in every country of the world and it is a question to what extent the oral medicines and dentifrice containing fluorides respectively are efficacious for the prevention of tooth decay.
Let us examine here the influence of fluorine upon the human body. Fluorine itself is one of the inorganic micro-elements in the human body and principally exists in the enamel of a tooth as well as in cartilage, skin, blood etc. The function of fluorine in the human body, however, remains unexplained. When ordinary drinking water in a region contains 2.7-5 ppm of fluorine, the region is called a fluorine region and this amount of fluorine may cause mottled tooth. It is regarded that a fluorine content of 1-2 ppm in the case of infants in particular and that of 0.8 ppm in the case of milk teeth may bring about a danger of outbreak of mottled tooth. On the other hand, as the flurine content in a decayed tooth is 0.0069% which is less than that of 0.0111% in a healthy tooth, it is considered that about 0.7 ppm of fluorine content in the drinking water is efficacious for the prevention of outbreak of tooth decay. But this amount alone does not make a perfect dental medicine against tooth decay. However, as a preventive measure against tooth decay in general, there are such methods as adding a little amount of fluorine to drinking water, application and addition of soda fluoride to dentifrice. Of the above, the addition of fluorine to drinking water is the most efficacious when it is conducted at the time when the teeth absorb calcium, or from the 4th month of pregnancy to one year in the case of milk teeth and before the age of 7 or 8 in the case of permanent teeth. Accordingly, the method of applying soda fluoride is the most efficacious when it is conducted before they cut their milk teeth and permanent teeth. Though fluorine has a function of reinforcing a formative substance of teeth as mentioned above, however, it has no function to kill bacilli. It is therefore impossible to remove causes of tooth decay only with fluorine and the application of fluorine is of no use when caries is already in an advanced stage. However, as mentioned above, water containing a soluble inorganic fluoride is efficacious for the prevention of caries and, making use of this property, various trials are made of adding soluble fluoric inorganics producing fluorine ion to dentifrice to put them to some use for the prevention of tooth decay.
As for such a soluble inorganic fluoride producing fluoric ion, it must be a substance which does no harm to the mucous membrane of the mouth, and the kinds are accordingly limited and only the fluoride of alkali metal such as soda fluoride, silicofluoride of the group of alkaline earths and tin fluoride or aluminum fluoride etc. are used under the existing circumstances. However, in the case of a dentifrice, when a soluble inorganic is added to such bases as calcium carbonate and calcium phosphate, ion dissociation takes place affected by the water contained in the dentifrice and the dissociated ion joins with calcium to become insoluble calcium fluoride resulting in eduction and, as this cannot penetrate into the tooth canaliculi, the prevention of tooth decay by fluorine ion proves inefficacious in practice. The reason why resin has come to be used as a material for dentifrice seems to lie in the fact that it does not contain polyvalent metallic ion. In spite of many efforts which have been exerted for the past tens of years to find out any satisfactory preventive medicine containing fluorine, nothing has so far been discovered which can satisfactorily be used by both dental surgeons and people in general. The fact that these sorts of dentifrice contain fluoric ions in the form which is difficult to be utilized seems to be the reason why they are not used with satisfaction as mentioned above.